The University of Toronto National Biology Competition 2001 Examination Time: 75 minutes Number of Questions: 50 To view the correct answer when you select the "Answer" button you must have Javascript enabled on your web browser (select Options, Network Preferences, and then Languages). When you click on the "Answer..." button, a small window will pop up. You MUST close it, by clicking on "Back To Test". If you do not do this, subsequent windows displaying the answer will not be visible. This document is best viewed with at least Netscape 3.0 or Internet Explorer 3.0 Answer Key General Instructions Do not open this booklet until you are instructed to do so. Print your name at the top of the exam booklet.
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The University of TorontoNational Biology Competition
2001 Examination
Time: 75 minutesNumber of Questions: 50
To view the correct answer when you select the "Answer" button you must have
Javascript enabled on your web browser (select Options, Network Preferences, and
then Languages).
When you click on the "Answer..." button, a small window will pop up. You MUST
close it, by clicking on "Back To Test". If you do not do this, subsequent windows
displaying the answer will not be visible.
This document is best viewed with at least Netscape 3.0 or Internet Explorer 3.0
Answer Key
General Instructions
Do not open this booklet until you are instructed to do so. Print your name at the top of the exam booklet.
Indicate all of your answers to the questions on the separate Response Form. No credit will be given for anything written in this booklet, but you may use the booklet for notes or rough work. No additional time will be given after the exam to transfer your answers to the Response Form.
After you have decided which of the suggested answers is best, COMPLETELY fill in the corresponding bubble on the Response Form. Give only one answer to each question. If you change an answer, be sure that the previous mark is erased completely.
Use your time effectively. Do not spend too much time on questions that are too difficult. Go on to other questions and come back to the difficult ones later if you have time. It is not expected that everyone will be able to answer all questions.
Should you guess the answers to questions about which you are not certain?
Since your score on the exam is based on the number of questions you answered correctly minus one-third of the number you answered incorrectly, it is improbable that guessing will improve your score (it is more likely to lower your score). (No points are deducted or awarded for unanswered questions.) However, if you are not sure of the correct answer but have some knowledge of the question and are able to eliminate one or more of the answer choices, then your chance of getting the right answer is improved, and it may be advantageous to answer such a question.
1. When a cell that was deprived of nutrients was given glucose, the pH within its vacuoles dropped. The best reason for this observation is that:
a. a starved cell pumps protons across the plasma membrane to the cell exterior.b. the dissociation of glucose in the vacuoles releases hydrogen ions.c. protons leave the vacuole by passive transport.d. protons enter the vacuole by passive transport. e. protons enter the vacuole by active transport.
2. Individuals afflicted with haemophilia suffer from excessive bleeding due to the failure of the normal clotting mechanism. The disease is associated with a sex-linked recessive gene. Two brothers are haemophiliacs; their parents do not suffer from excessive bleeding. The probability that their sister inherited the gene for haemophilia is most likely:
a. 0b. 1/4c. 1/2d. 3/4e. 1
3. If you arranged the units of life listed in the table below into a hierarchy, from smallest (least inclusive) to largest (most inclusive), which unit would be found three levels below a fish?
Organism
Community Molecule
AtomPopulatio
nOrgan
Tissue CellBiosphere
a. Organb. Biospherec. Moleculed. Celle. Population
4. Which of the following best describes Darwin's theory of the mechanism of genetic inheritance?
a. Inheritance of acquired characteristicsb. Blending inheritancec. Molecular inheritanced. Particulate inheritancee. Adaptive inheritance
5. In the absence of oxygen, cells capable of fermentation:
a. accumulate glucose.b. no longer produce ATP.c. accumulate pyruvate.d. oxidize FAD.e. oxidize NADH to produce NAD+.
6. Which statement is FALSE?
a. Cells that do not divide are usually arrested in the G2 phase.b. Within the centrosome of an animal cell are a pair of centrioles.c. The kinetochore is the point of attachment of the spindle fibre to the chromatid.d. Anaphase begins the instant that the sister chromatids begin to separate.e. A nucleosome consists of part of the DNA molecule wrapped around a group of histone molecules.
7. What is the difference between an acid and a base?
a. An acid undergoes a reversible reaction, while a base does not.b. An acid releases OH- ions in solution, while a base accepts OH- ions.c. An acid releases OH- ions in solution, while a base releases H+ ions.d. An acid releases H+ ions in solution, while a base accepts H+ ions.e. Acidic solutions have higher concentrations of OH- than H+ , while basic solutions have higher concentrations of H+ than OH-.
8. If the inner surface of the ileum in the human small intestine were smooth, rather than being folded and subdivided into villi, which statement would be true?
a. The rate of absorption of digested food molecules would be higher, because the digested food would pass more easily through the digestive tract.b. Digestion would not be as effective, because there would be fewer cells secreting trypsin (a protein-digesting enzyme).c. Humans would have needed to evolve a much longer small intestine to absorb sufficient nutrients from their food.d. Humans would not be able to survive, because the digestive tract would be more susceptible to damage.e. Utilization of cellulose in the diet would not be possible, because the microorganisms that digest cellulose would have nowhere to live.
9. The total biomass in a terrestrial ecosystem will be greatest for which trophic level?
a. Herbivoresb. Producersc. Primary consumersd. Tertiary consumerse. Secondary consumers
10. After pollination, which of the following events is crucial for fertilization to occur in flowering plants?
a. Sperm swim to the egg and the polar nuclei.b. Petals close around the reproductive parts.c. Meiosis occurs within the pollen grain.d. A pollen tube grows from the stigma to the ovule.e. An insect delivers pollen to the stigma.
11. Plant hormones play a role in regulating seed germination. The graph below shows changes in hormone concentrations (left axis) and hypocotyl growth (right axis) over time for mung bean. Which hormone(s) most likely regulates hypocotyl (bean sprout) growth during mung bean germination?
a. Gibberellic acid aloneb. Auxin alonec. Abscisic acid alone
d. Both auxin and gibberellic acide. Both auxin and abscisic acid
12. What is the most likely explanation for the observation that two individuals originating from the same clone look different?
a. They developed in different environments.b. They are differentially adapted to the same environment.c. The clone from which they originated had more than one genotype.d. They differ in heterozygosity.e. They differ in homozygosity.
13. In the context of evolution, what is the most important source of new mutations?
a. Exposure to x-rays.b. Exposure to ultra-violet radiation.c. Exposure to chemicals.d. The mispairing of chromosomes during meiosis.e. Errors during DNA replication.
14. Which statement is CORRECT?
a. The vacuole is usually the largest organelle found in plant cells.b. Plants do not have mitochondria.c. Nuclei do not contain proteins.d. The Golgi complex is primarily made up of microtubules.e. The lysosome is only found in prokaryotic cells.
15. In a microbiology laboratory, the technician uses heat to sterilize the nutrient solution that is used to grow a fungus. When the heating system broke down, he sterilized the solution by passing it (in a sterile environment) through a sterile filter with a pore size of 0.2 micrometers. When the fungus was grown on the filtered nutrient solution it stopped growing and looked unhealthy within a
few days. Which statement is the most likely explanation for the observed effect on the fungus?
a. The nutrient solution contained a virus.b. Heating makes the glucose in the nutrient solution more digestible.c. Filtering removed one of the larger nutrient molecules.d. The nutrient solution contained a bacterium that was pathogenic to the fungus.e. Filtering changed the pH of the nutrient solution.
16. Which factor would contribute the most to increasing the rate of water movement upward in the xylem?
a. The generation of root pressure.b. The availability of soil water.c. The rate of transpiration from the leaves.d. The rate of carbohydrate loading.e. The rate of auxin synthesis.
17. Two alternative alleles, the dominant A and the recessive a, are in equilibrium in a population. The frequency of A is 0.6. The percentage of individuals showing the dominant trait in the population should be:
a. 36%b. 40%c. 60%d. 75%e. 84%
18. Fertile hybrids between different plant species are common in nature and form much of the basis for plant breeding in horticulture and agriculture. The plant species pairs involved in forming fertile hybrids are consistent with:
a. both the biological and the morphological species concepts.b. the biological but not the morphological species concept.c. the morphological but not the biological species concept.
d. neither the biological nor the morphological species concept.e. all of the species concepts that have been proposed.
19. Which of the following is incorrectly paired with its function?
a. Epididymis: maturation and storage of sperm.b. Prostate gland: secretes testosterone, a male sex hormone.c. Fallopian tube: catches ova and conducts them towards the uterus.d. Seminal vesicles: produce a sugar-containing fluid to nourish sperm.e. Corpus luteum: produces progesterone, a female sex hormone.
20. What was the key evolutionary event that led to the diversification of plants on land? The evolution of:
a. chloroplasts.b. protected seeds.c. tissues to store starch.d. meiosis.e. a water-conducting cell type.
21. Which statement about animal stem cells is FALSE?
a. Stem cells are relatively undifferentiated cells that can divide to produce more differentiated tissue cells.b. Stem cells can be found in tissues that need frequent cell replacement, such as skin, the inner lining of the intestine, and the blood system.c. Dividing stem cells can produce cells that differentiate to replace cells lost to injury and age; for example, stem cells in bone marrow produce red and white blood cells.d. Scientists are able to grow stem cells in the laboratory.e. Recent studies have shown that stem cells from one kind of tissue cannot be made to differentiate into cells of another tissue.
22. What two characteristics make water different from most other compounds?
a. Its solid state is less dense than its liquid state, and it takes up large amounts of heat to change to its gaseous state.b. Its solid state is less dense than its liquid state, and it takes up only small amounts of heat to change to its gaseous state.c. Its solid state is more dense than its liquid state, and it takes up large amounts of heat to change to its gaseous state.d. Its solid state is more dense than its liquid state, and it takes up only small amounts of heat to change to its gaseous state.e. Its solid state is just as dense as its liquid state, and it takes up no heat to change to its gaseous state.
23. In Drosophila the gene for brown eyes is recessive to its normal allele for red eyes; the gene for curled wings is recessive to its normal allele for straight wings. The two genes show independent assortment. Males heterozygous for both genes are mated to females that are heterozygous for the eye colour gene, but homozygous for the gene for curled wings. What proportion of the offspring should have normal red eyes and normal straight wings?
a. 3/16b. 3/8c. 1/2d. 3/4e. 9/16
24. Some plants contain nitrogen-fixing bacteria (of the genus Rhizobium) in their root nodules. This relationship is known as:
a. an amensalism (one participant harms the other).b. a commensalism (one participant benefits but has no effect on the other).c. a mutualism (both participants benefit).d. interspecific (between species) competition.e. competitive exclusion (competition between species for a limiting resource in which one species completely eliminates the other).
25. Populations of many species of small mammals – such as lemmings, voles, and snowshoe hares in Canada – undergo large population fluctuations on a predictable basis (e.g., every 3 to 4 years). Which of the following does NOT appear to play a role in these population cycles?
a. Territorial (spacing) behaviour of adult members of these populationsb. Dispersal of individuals away from the area where they were bornc. Stress caused by the effects of living at high densitiesd. High mortality caused by predatorse. Severe weather conditions
26. Natural selection is a process that may result in evolution. If evolution is to occur, which of the following must be true?
i. Individuals within a species are variable.
ii. Some of the variations within species are passed on to the offspring (i.e., they
are inherited).
iii. More individuals are produced than the environment can support; only a
fraction of the offspring produced in each generation survive to reproduce.
iv. The survival and reproduction of individuals are not random; the individuals
who survive and go on to reproduce, or who reproduce the most, are those with
the most favourable variations.
a. i, ii and iiib. i, ii and ivc. i, ii, iii and ivd. iii onlye. iv only
27. Cell division in plants is typically concentrated in meristems. In which of the following regions of the plant would cell division NOT occur?
a. Shoot apexb. Root apexc. Embryod. Woode. Cambium between wood and bark
28. DNA fingerprinting has become a familiar forensic tool and has been cited in recent criminal trials. It is possible to do DNA fingerprinting with even a very minute sample of DNA because:
a. DNA contains only four different types of nitrogenous bases.b. there are large quantities of DNA in each cell of the body.|c. DNA determines a very specific polypeptide chain.d. one can use the polymerase chain reaction.e. gel electrophoresis is very effective.
29. Which statement about geographical speciation is FALSE? The diverging populations:
a. initially belong to the same species.b. become genetically differentiated from one another.c. acquire some degree of reproductive isolation.d. may respond to natural selection.e. live in the same geographical region.
30. Coupled biochemical reactions are important in determining thermodynamic order within cells. The figure below shows two hypothetical reactions, I and II. Which statement about these reactions is FALSE?
a. The splitting of ATP to ADP + Pi releases about 7.3 kcal/mole.b. The reaction of compound A to produce compound B requires an input of about 4 kcal/mole, which is provided by reaction II.
c. Reaction I is exergonic, yielding 4 kcal/mole.d. The two coupled reactions release about 3.3 kcal/mole.e. To drive reaction I, the splitting of ATP to ADP + Pi is always required.
31. The content of a large vacuole in a eukaryotic cell has the same osmotic pressure as the surrounding cytoplasm, to prevent it from shrinking or bursting. If this eukaryotic cell is placed in a 3 M sucrose solution:
a. the cell would burst.b. the vacuole would expand and burst.c. the cell and the vacuole would both shrink.d. the cell would shrink but the vacuole would remain the same size.e. nothing would happen, because a 3 M sucrose solution has the same osmotic pressure as the cell cytoplasm.
32. Which statement is CORRECT?
a. Membranes of living organisms are in a fluid state, rather than in a gel state.b. Membranes are semipermeable: large molecules such as proteins can easily move across them.c. Hydrophilic organic molecules easily diffuse across membranes in eukaryotic cells.d. In plants, the plasma membrane is known as the cell wall.e. Rough endoplasmic reticulum is the name given to clusters of ribosomes attached to the cytoskeleton.
33. The sequence of steps in cellular respiration is:
a. Pyruvate oxidation --> electron transport chain citric --> acid (Krebs) cycleb. Pyruvate oxidation --> citric acid (Krebs) cycle --> electron transport chainc. Citric acid (Krebs) --> cycle pyruvate oxidation --> electron transport chaind. Citric acid (Krebs) --> cycle electron transport chain --> pyruvate
oxidatione. Electron transport chain --> pyruvate oxidation --> citric acid (Krebs) cycle
34. Which statement about the mammalian circulatory system is CORRECT?
a. The average diameter of arteries is greater than that of veins.b. The order of decreasing velocity of blood flow is: arteries > capillaries > veins.c. The total surface area of the capillaries is considerably greater than that of all of the arteries, arterioles, venules, and veins combined.d. In order to return blood to the heart, the blood pressure in veins is higher than it is in the capillaries.e. The electrical activity that coordinates the beating of the heart originates in the atrio-ventricular node.
35. According to the latest estimates of the total number of human genes (based on the findings of the Human Genome Project) there are:
a. less than 20,000 genes.b. 30,000 to 50,000 genes.c. 200,000 to 400,000 genes.d. 500,000 to 1 million genes.e. over 3 million genes.
36. Which statement about the "foreign" genetic material in genetically modified (GM) crop plants or animals is FALSE?
a. It must be inserted again in each generation.b. It alters the phenotype of the GM plant or animal.c. It may be subject to artificial selection by breeders and farmers.d. It may be subject to natural selection by weather, pests, and diseases.e. It may be transferred to related non-crop plants or animals.
37. Which statement about the two pathways of photosynthesis is FALSE?
a. The first pathway (the light reactions) captures light energy and produces ATP and NADPH + H+.b. The second pathway (the Calvin-Benson cycle) uses the products of the first pathway and CO2 to produce sugars.c. The second pathway is also known as the dark reactions because none of its reactions uses light directly.d. The light reactions occur within chloroplasts; the Calvin-Benson cycle takes place in the cytosol.e. Both pathways stop in the dark.
38. If it was possible to genetically engineer humans to be able to run long distances faster at high altitudes, which of the following would NOT help?
a. Increasing the thickness of the cellular lining of the alveoli.b. Increasing the amount of haemoglobin in each red blood cell.c. Decreasing the binding affinity of oxygen and haemoglobin at very low oxygen partial pressures.d. Decreasing the average size of the alveoli.e. Increasing maximum cardiac output.
39. Which pattern of evolutionary change has NOT been recognized in portions of the fossil record that have been thoroughly sampled?
a. Rapid change from one species to another over a short period of time (punctuation)b. Rapid change from one family or order to another over a short period of time (saltation)c. Stasis (equilibrium)d. Gradual changee. Fluctuating change
40. In the event of global warming which one of the following is most likely to occur?
a. Existing plant and animal communities will move north in response to warming.b. Agriculture in the Prairie provinces will be redeveloped on soils of the Canadian Shield.c. The anticipated rise in sea level will be caused primarily by the melting of polar ice caps.d. The decomposition of organic matter in the unfrozen surface layer of polar soils will increase.e. Tundra vegetation will increase in area as soils dry out in polar regions.
41. Macromolecules are giant molecules formed by the joining of smaller molecules. The bonds that form between the units of macromolecules are:
42. Which of the following is NOT a function of the mammalian kidney?
a. Water retentionb. Regulation of sodium in the bloodc. Excretion of toxinsd. Synthesis of ureae. Water excretion
43. In what respects are the photosynthetic adaptations of C4 plants and CAM plants similar?
a. In both cases, the stomata normally close during the day.b. Both types of plants make their sugar without the Calvin-Benson cycle.c. In both cases, an enzyme other than rubisco carries out the first step in carbon fixation.
d. Both types of plants make most of their sugar in the dark.e. Neither C4 plants nor CAM plants have grana in their chloroplasts.
44. A scientist discovered that a protein associated with the plasma membrane of a cultured animal cell disappeared from the membrane soon after a hormone was added to the cell. After adding the hormone, if she disrupted the cell and centrifuged it, the protein did not stay in solution but went to the bottom of the centrifuge tube. After adding the hormone, if she disrupted the cell and dissolved all membranes with a detergent before centrifuging, the protein remained in solution. Which statement best explains her results?
a. The protein was a peripheral membrane protein that came off the membrane after hormone treatment.b. The hormone caused the cell to make endocytotic vesicles that specifically formed at sites in the plasma membrane that contained the protein.c. The hormone destroyed the protein.d. The hormone bound to the protein to make the protein heavier.e. The hormone caused the plasma membrane to break into fragments, causing the cell to make new plasma membrane without the protein.
45. Which of the following is NOT involved in DNA replication?
a. Helicaseb. RNA primasec. Reverse transcriptased. DNA ligasee. DNA polymerase
46. If an adult human female took a drug that inhibited the release of LH (luteinizing hormone), which of the following would NOT occur?
a. The menstrual cycle.b. Release of an ovum from a mature follicle.
c. Secretion of FSH (follicle stimulating hormone) from the pituitary.d. Secretion of estrogen by the follicle cells.e. Secretion of GnRH (gonadotropin-releasing hormone) from the hypothalamus.
47. How does a noncompetitive inhibitor inhibit binding of a substrate to an enzyme?
a. It binds to the substrate.b. It binds to the active site.c. It lowers the activation energy.d. It increases the change in free energy ( G) of the reaction.e. It changes the shape of the active site.
48. The figure below shows two nerve action potentials recorded intracellularly in response to stimulating an axon. What experimental manipulation would most likely have caused the change from curve A (solid line) to curve B (dashed line)?
a. A decrease in stimulus intensity.b. A decrease in sodium concentration in the extracellular fluid.c. A decrease in the potassium concentration inside the neuron.d. The presence of a low concentration of tetrodotoxin, a sodium-channel blocker.e. An increase in intracellular calcium concentration.
49. Thermoregulation in mammals is a balance between heat gain and heat loss. All of the following can affect both heat gain and heat loss EXCEPT:
a. Activity of the sweat glands.b. Thickness of the fat layer under the skin.c. Air movement near the body surface.d. Blood flow in the skin.e. Colour of the body surface.
50. Which statement is FALSE?
a. Nondisjunction refers to the failure of a pair of chromosomes to segregate during meiosis.b. Karyotype refers to the number, forms, and types of chromosomes in a cell.c. Autosomes are cytoplasmic organelles that contain DNA and are capable of self-replication.d. Prophase refers to the onset of nuclear division.e. Centromere refers to the region where sister chromatids join.
The University of Toronto National Biology Competition
On the original test paper (May 2001) there were two correct responses in
each of questions 7 and 38; these have been corrected on the online version of
the test. This was unintentional. If a student selected either of the responses it
was recorded as a correct response.
Question 7 asked "What is the difference between an acid and a base?". Response (d), "An acid releases H+ ions in solution, while a base accepts H+ ions," is the definition (the Brønsted-Lowry definitnion) used most often in biology. Credit was also given to students who selected (e), "An acid releases H+ ions in solution, while a base releases OH ions;" this definition (the Arrhenius definition) is often taught to students in general science classes.
In question 38, both (a) and (d) are correct statements (i.e, they would not help genetically-engineered humans to be able to run long distances faster at high altitudes). To be an incorrect statement (d) should have stated: "Decreasing the average size of the alveoli while keeping their total volume constant."
The University of TorontoNational Biology Competition
2000 Examination
Time: 75 minutesNumber of Questions: 50
NOTE:
To view the correct answer when you select the "Answer" button you must have Javascript
enabled on your web browser (select Options, Network Preferences, and then Languages).
When you click on the "Answer..." button, a small window will pop up. You MUST close
it, by clicking on "Back To Test". If you do not do this, subsequent windows displaying
the answer will not be visible.
This document is best viewed with at least Netscape 3.0 or Internet Explorer 3.0
Answer Key
General Instructions
Do not open this booklet until you are instructed to do so. Print your name at the top of the exam booklet.
Indicate all of your answers to the questions on the separate Response Form. No credit will be given for anything written in this booklet, but you may use the booklet for notes or rough work. No additional time will be given after the exam to transfer your answers to the Response Form.
After you have decided which of the suggested answers is best, COMPLETELY fill in the corresponding bubble on the Response Form. Give only one answer to each question. If you change an answer, be sure that the previous mark is erased completely.
Use your time effectively. Do not spend too much time on questions that are too difficult. Go on to other questions and come back to the difficult ones later if you have time. It is not expected that everyone will be able to answer all questions.
Good luck and have fun!
Should you guess the answers to questions about which you are not certain?
Since your score on the exam is based on the number of questions you answered correctly minus one-third of the number you answered incorrectly, it is improbable that guessing will improve your score (it is more likely to lower your score). (No points are deducted or awarded for unanswered questions.) However, if you are not sure of the correct answer but have some knowledge of the question and are able to eliminate one or more of the answer
choices, then your chance of getting the right answer is improved, and it may be advantageous to answer such a question.
1. Today there are many different breeds of dogs. What mechanism is responsible for most of this variation?
a. Inbreeding
b. Genetic drift
c. Natural selection
d. Artificial selection
e. Gene flow
2. In the evolution of life on Earth the early primitive cells that were present must have obtained their energy by:
a. glycolysis and fermentation.
b. aerobic respiration.
c. cyclic phosphorylation.
d. noncyclic phosphorylation.
e. oxidative phosphorylation.
3. The excessive use of antibiotics is a concern to the medical community. The concern is that antibiotics will no longer be as effective in treating disease because:
a. humans are evolving a resistance to some antibiotics.
b. viruses are not killed by antibiotics.
c. some bacteria are evolving resistance to antibiotics.
d. antibiotics are very expensive.
e. antibiotics cause mutations.
4. Which of the following "vegetables" is technically a fruit?
a. Potato
b. Lettuce
c. Broccoli
d. Celery
e. Green bean
5. The concentration of polychlorinated biphenyls (PCB, an organochloride contaminant) in many fish populations has been declining since a ban on their production was instituted in the late 1970s. PCBs remain a potential problem, however, because they are lipophilic and are known to biomagnify. Based on this knowledge, what type of fish is expected to be safest for human consumption (i.e., with the lowest concentration of organochlorides)?
a. Slow-growing fish species.
b. Piscivorous fish species (i.e., which eat other fish).
c. Benthivorous fish species (i.e., which eat invertebrates on the lake bottom).
d. Small (young) fish.
e. Fish species with high fat content.
6. Which statement about chemical bonds is CORRECT?
a. A covalent bond forms between a sodium ion and a chloride ion.
b. A hydrogen bond forms between water molecules.
c. A hydrophobic interaction links an oxygen atom to the hydrogen atoms in a
water molecule.
d. A covalent bond links an iron atom to the protein haemoglobin.
e. An ionic bond binds complementary base pairs together in a double-stranded
DNA molecule.
7. Which of the following statements about atoms are CORRECT?
i. The atoms which make up an element are usually of the same kind.
ii. An atom is identified by the number of its protons, which is called the atomic
number.
iii. Not all atoms of the same element have the same mass number.
iv. Deuterium and tritium are isotopes of hydrogen; all three have the same
atomic number, 1.
a. i and ii
b. i, ii, iii, and iv
c. i and iii
d. ii and iv
e. iii and iv
8. Thyroid stimulating hormone (TSH), luteinizing hormone (LH), and oxytocin are all:
a. released from the pituitary gland.
b. tropic hormones (act on other endocrine tissue).
c. steroid hormones.
d. sex hormones.
e. involved in the regulation of blood glucose.
9. Why is the global climate change that is predicted to occur in the next 100 years a concern for ecological communities?
a. Primary production will decline markedly due to decreased atmospheric CO2
concentrations.
b. The tundra of northern polar regions will disappear and be replaced by boreal
forest.
c. Species will not be able to migrate quickly enough to follow the change in
climate.
d. Ocean levels will increase substantially and flood a large portion of present
continents.
e. Ultra-violet (UV) radiation will increase and have a severe impact (e.g.,
deleterious mutations) on communities worldwide.
10. Gas exchange in animals always involves:
a. cellular respiration.
b. breathing movements.
c. active transport of gases.
d. control by the central nervous system.
e. diffusion across membranes.
11. The graph below shows how much nitrate (NO3-) is exported
from the continent towards the ocean by 16 major rivers in the world compared to the density of human populations living in those
drainage basins (i.e., along these rivers). Nitrate exported through rivers causes eutrophication and has been implicated in the development of toxic algal blooms in marine coastal regions. What conclusion drawn from the graph is CORRECT?
a. Large drainage basins export more NO3-.
b. Small drainage basins export more NO3-.
c. Drainage basins with higher population densities export more NO3-.
d. Drainage basins with lower population densities export more NO3-.
e. All rivers export equally large amounts of NO3-.
12. Which statement about proteins is CORRECT?
a. The primary structure of a protein is composed of many branched chains.
b. Proteins always contain an amino group at one end and the amino acid
methionine at the other end.
c. The formation of disulfide bridges between cysteine amino acids can modify a
protein's primary structure.
d. Charged amino acids are frequently found in the hydrophobic interior of a
folded protein.
e. The quaternary structure of proteins is the result of the interactions of two or
more independent polypeptide chains.
13. One aspect of genetic engineering involves the modification of proteins to improve their function. Which statement would NOT be a logical goal for researchers in this field?
a. Increase the hydrophobicity of a protein so that it will function in the aqueous
environment of the cell cytoplasm.
b. Improve the binding of a specific substrate to an enzyme.
c. Modification of an enzyme active site to increase the rate of catalysis.
d. Increase the stability of a protein so that it may function at a higher
temperature.
e. Change the amino acid content of the protein to improve its value as a more
nutritious food for animals or humans.
14. A scientist isolated pieces of plasma membrane from an animal cell and put them in an apparatus so that the membrane separated two reservoirs of distilled water. When she added a dilute solution of acetic acid to one side (side A) of the membrane, the pH of the solution on the other side (side B) did not change. She then ground up a culture of animal cells, filtered out the organelles and bits of membrane, and added this cell extract to side A. The pH of the solution in side B then dropped. What is the most reasonable explanation for the drop in pH in side B?
a. The cell extract contained lipids that dissolved in the membrane.
b. The cell extract caused the acetic acid to dissociate.
c. Protons moved across the membrane by diffusion.
d. Protons moved across the membrane by passive transport.
e. Protons moved across the membrane by active transport.
15. Which of the following organelles from a living specimen can NOT be observed under the light microscope (using a x100 objective)?
a. The nucleus of a plant cell.
b. Ribosomes in an animal cell.
c. Chloroplasts in a plant cell.
d. The nucleolus of an animal cell.
e. Mitochondria in a plant cell.
16. Some single-celled, non-photosynthetic organisms have a water expulsion vacuole that collects water from the cytoplasm and expels it from the cell. If you were trying to grow one of these organisms in the laboratory, which growth medium would be closest to its natural habitat? A dilute, aqueous, nutrient solution:
a. supplemented with 1M NaCl.
b. supplemented with 1M sucrose.
c. supplemented with 1M glucose.
d. supplemented with 1M KCl.
e. with no supplements.
17. Jean Baptiste Lamarck published his theory of evolution in 1809, the year that Charles Darwin was born. Lamarck's theory of evolution has been rejected by modern biologists because:
a. his theory provided a genetic mechanism for how evolutionary change
occurred.
b. his theory was based on special creation.
c. the selection experiments he conducted on giraffe's necks involved artificial
and not natural selection.
d. the characteristics an organism acquires during its lifetime cannot be passed on
to its offspring.
e. his theory was only applicable to humans.
18. Which statement about mitosis and the eukaryotic cell cycle is FALSE?
a. Telophase is defined as the stage at which all the kinetochores arrive at the
equatorial plate and the centromeres begin to divide.
b. Replication of DNA occurs during the S phase of the cell cycle, which is part
of interphase.
c. At the onset of mitosis, the chromatin becomes highly organized as a result of
supercoiling and compacting.
d. Mitosis refers only to the division of the nucleus, but is most often followed by
cytokinesis, the division of the cell.
e. The transition of the cell from the G2 phase to the M phase requires the action
of cyclins.
19. Which statement about photosynthesis is FALSE?
a. In green plants, both photosystems I and II are required for the synthesis of
NADPH+H+.
b. The first stable product of photosynthesis in the majority of green plants (C3-
type plants) is 3-phosphoglycerate.
c. In normal aerobic environments and saturating levels of light, an increase in
CO2 concentration from 0.03% to 0.06% (300 ppm to 600 ppm) will result in an
increase in the rate of CO2 fixation by most green plants (C3-type plants).
d. Photosynthesis is a redox process: H2O is oxidized, CO2 is reduced.
e. The enzymes required for CO2 fixation in plants are located only in the grana
of the chloroplast.
20. Feather colour in budgies is determined by two different genes that affect the pigmentation of the feathers: Y_B_ is green; yyB_ is blue; and yybb is white. Two blue budgies were paired for life. Over many years, they produced 22 offspring, five of which were white. What are the most likely genotypes for the parents?
a. yyBB and yyBB
b. yyBB and yyBb
c. yyBb and yyBb
d. yyBB and yybb
e. yyBb and yybb
21. A man is brought to court in a paternity case. He has blood type B, Rh positive. The mother has blood group B, Rh negative. The child's blood type is A, Rh negative. Which statement about the man is CORRECT?
a. He is the father.
b. He might be the father.
c. He is not the father.
d. He might not be the father.
e. There is not enough information to make a decision.
22. A trait in a hypothetical diploid organism is inherited via a single gene with four different alleles. How many different genotypes would be possible in this system?
a. 3
b. 6
c. 8
d. 10
e. 16
23. How are mature human sperm and ova similar?
a. They are approximately the same size.
b. They are formed before birth.
c. They each have a flagellum that provides motility.
d. They are produced from puberty until death.
e. They both have the same number of chromosomes.
24. The frequency of crossing over between any two linked genes is:
a. higher if they are recessive.
b. difficult to predict.
c. determined by their relative dominance.
d. the same as if they were not linked.
e. proportional to the distance between them.
25. Which statement concerning living eukaryotic cells is FALSE?
a. Membranes control which hydrophilic organic molecules pass into or out of
the cell.
b. Lysosomes and centrioles are each bounded by a single membrane.
c. Membranes are usually fluid at 37C.
d. Membranes contain phospholipids and proteins.
e. Membranes are semipermeable.
26. There was great excitement around the world when the sheep "Dolly" was cloned using a nucleus derived from an adult cell of its
"mother" which was then transplanted into an enucleated egg. There is also excitement when it is announced that genes causing human diseases, like muscular dystrophy, have been cloned. Which statement about these two examples of cloning is CORRECT?
a. They both involve cutting a piece of DNA from the genome.
b. One involves the cloning of a nucleus and the other is the cloning of a piece of
DNA.
c. They both produce products genetically identical to the original donor of
cellular material.
d. They raise no ethical questions.
e. They are similar to deriving a bacterial clone from a single bacterial cell which
divides to form a colony.
27. All fungi:
a. are parasitic.
b. are capable of carrying out photosynthesis.
c. are heterotrophic.
d. live on dead organic matter.
e. are pathogens.
28. On the Galapagos Islands evolutionary divergence has resulted in 14 species of finches that are differentially adapted to feed on seeds, insects, and the buds of various plant species. This example of adaptive radiation occurred because the Galapagos Islands are:
a. close enough to one another to favour considerable inter-island migration.
b. close to the mainland.
c. small, favouring divergence through genetic drift alone.
d. arid and stressful, resulting in many mutations.
e. sufficiently isolated from one another that inter-island migration rarely occurs.
29. NaCl is harmful to most crop plants. A scientist at the University of Toronto genetically modified a plant so that it could be grown in dry parts of the world where the available water has a high level of NaCl. This genetically modified plant copes with the high levels of NaCl by transporting salt into its vacuoles where it accumulates to
abnormally high levels. Which feature would be observed in the genetically modified plant when compared to a non-modified plant?
a. The leaves in the modified plant are more yellow in colour.
b. The modified plant has salt crystals on the surface of its leaves.
c. The cytosol (the material between the plasma membrane and the vacuole
membrane, excluding the organelles) in the modified plant has a lower osmotic
pressure.
d. The cytosol in the modified plant has a higher osmotic pressure.
e. The osmotic pressure is the same in both plants.
30. Which statement about ATP synthesis is FALSE?
a. ATP is synthesized only in chloroplasts and mitochondria.
b. ATP synthesis in the chloroplast occurs in the thylakoid region of this
organelle.
c. Proton motive force (proton gradient) drives the formation of ATP in
mitochondria.
d. ATP synthases are protein complexes that allow protons to cross membranes.
e. Substrate level phosphorylation of ADP does not require ATP synthase to
catalyse the reaction.
31. Dominant mutations are easier to detect than recessive mutations because they:
a. are always lethal and so their appearance is unmistakable.
b. are expressed in both homozygotes and heterozygotes.
c. occur at a higher frequency.
d. are always neutral in their effect.
e. are always favoured by selection.
32. A man who carries an X-linked allele will pass it on to:
a. all of his daughters.
b. half of his daughters.
c. all of his sons.
d. half of his sons.
e. all of his children.
33. The main feature of the "biological species concept" is its emphasis on the:
a. large morphological differences between different species.
b. genetic variation within populations.
c. recognition of different species based on their ecological separation.
d. role of sexual reproduction in maintaining diversity within a species.
e. absence of gene flow between different species.
34. Which statement about genetically modified (GM) foods is FALSE?
a. Scientists have used genetic modification, in various forms, as a means of
improving crop yields, crop quality, and pest resistance for many years.
b. Genetic modification includes products made by artificial mutagenesis and by
non-natural crosses between unrelated species.
c. A major difficulty in labelling foods as "GM-free" is that it is virtually
impossible to measure genetically modified DNA or protein molecules in most
foods made from GM crops.
d. The recent decision by McCain Foods to stop processing GM potatoes means
that they will eventually use less pesticides to produce the potatoes that are
required to make fries.
e. A major environmental concern with GM crops is that engineered genes will
escape into the environment, resulting in the origin of "superweeds" (aggressive
undesirable plant species).
35. Of the following taxonomic categories which is the most inclusive (i.e., is the highest in the hierarchy)?
a. Order
b. Subspecies
c. Class
d. Genus
e. Family
36. Some viruses are surrounded by a membranous envelope which originates from the:
a. plasma membrane of the host cell.
b. synthesis of proteins and lipids inside the virus.
c. synthesis of proteins in the virus and lipids in the host cell.
d. synthesis of lipids in the virus and proteins in the host cell.
e. nucleus of the host cell.
37. In plants, sieve areas are regions of the cell wall with pores that allow cytoplasmic continuity between adjacent:
a. epidermal cells.
b. parenchyma cells.
c. phloem cells.
e. tracheids.
e. xylem vessels.
38. If the haploid number for a species is three, each dividing diploid cell during mitosis will have how many chromatids at anaphase?
a. 3
b. 6
c. 9
d. 12
e. 18
39. A feature of fertilization that is only found in angiosperms is that:
a. the sperm may be carried by wind to the female organ.
b. one sperm fertilizes the egg, while another combines with the polar nuclei.
c. a pollen tube carries a sperm nucleus into the female gametophyte.
d. a chemical attractant guides the sperm towards the egg.
e. the sperm cells have flagella for locomotion.
40. Which statement about mammalian heart function is FALSE?
a. Contraction of the heart originates at the sinoatrial node in the right atrium.
b. The atrioventricular node propagates the contraction to the ventricles.
c. During atrial contraction venous blood flows into the right ventricle.
d. The pulmonary artery contains oxygenated blood.
e. The left side of the heart pumps only oxygenated arterial blood.
41. The main effect of cytokinins in plants is to:
a. increase the length of internodes on flowering stems.
b. prevent the growth of lateral buds.
c. regulate opening and closing of stomata.
d. stimulate cell division.
e. improve the quality of fruits.
42. In the following list, which term is LEAST related to the others?
a. Duplication
b. Inversion
c. Translocation
d. Nondisjunction
e. Deletion
43. In the central nervous system the amount of voltage change required to open enough sodium channels to initiate a nerve impulse is referred to as the:
a. refractory potential.
b. threshold potential.
c. action potential.
d. polarization potential.
e. resting potential.
44. Which statement about glycolysis is FALSE?
a. During glycolysis, glucose is metabolized to pyruvate with the formation of
ATP and NADH+H+.
b. The initial step in glycolysis requires the phosphorylation of glucose by the
enzyme phosphoglucomutase.
c. The conversion of phosphoenolpyruvate to pyruvate is catalysed by the
enzyme pyruvate kinase and results in the formation of ATP.
d. The end product of glycolysis, pyruvate, can be used by yeast to produce
ethanol during fermentation.
e. Glycolysis occurs outside the mitochondria.
45. The Swift Fox is a small mammal (about the size of a cat) that once lived throughout the prairie grasslands of central Canada. However, due to a number of factors including hunting, it had completely disappeared from Canada by the late 1970s. In an attempt to restore this species, foxes from American populations have been released in Canada. However, the number of Swift Foxes in Canada still remains low. Which factor is most likely NOT contributing to this?
a. Much of the fox's original grassland habitat has been replaced with agriculture,
which has reduced the quality and quantity of habitat for the foxes and the
availability of suitable prey.
b. The foxes released in early reintroductions did not survive well, likely due to a
lack of knowledge of sources of food and den locations, or because the American
foxes were not adapted to the longer Canadian winters.
c. Coyotes, which are increasing in numbers, are feeding on the foxes, or
competing with the foxes for available resources.
d. Swift foxes are still being trapped for their pelts (fur), as they have been since
the early 1800s.
e. Swift foxes may have been the unintended victim of trapping and poisoning
campaigns directed at other mammals, such as coyotes, wolves, and ground
squirrels.
46. Carbonic anhydrase is an enzyme in red blood cells that catalyses a reaction between carbon dioxide and:
a. bicarbonate.
b. carbonic acid.
c. haemoglobin.
d. oxygen.
e. water.
47. A certain type of grass has a diploid chromosome number of 8. A similar species of grass has a diploid chromosome number of 10. Interspecific hybridization between the two species results in sterile hybrids that can, nonetheless, reproduce vegetatively. The diploid chromosome number of these hybrids would be:
a. 9
b. 16
c. 18
d. 20
e. 36
48. Various regions of the three embryonic germ layers in vertebrates develop into organs and tissues in the adult. Which match is FALSE?
a. Mesoderm - notochord
b. Endoderm - lungs
c. Ectoderm - liver
d. Mesoderm - muscular system
e. Ectoderm - eye
49. Which characteristic is shared by ammonia, urea, and uric acid?
a. They are all nitrogenous wastes.
b. They all need large amounts of water for excretion.
c. They all require about the same amount of energy to produce.
d. They are all equally toxic.
e. They are all produced in the kidney.
50. You are studying two populations of a species of aquatic insect in two different ponds. Both populations go through several generations each summer. The per capita food supply is the same in both pools throughout the year and it is evenly distributed throughout the water column. You find that the population in pond A is increasing in numbers at a faster rate than the population in pond B. Which observation is most likely NOT contributing to this pattern?
a. Individuals in pond A have more offspring than individuals in pond B.
b. Individuals in pond A have smaller offspring than individuals in pond B.
c. Individuals in pond A mature at a younger age than individuals in pond B.
d. There is a predator that rarely preys on this species but it is enough of a
threat that it scares this species of insect into hiding in the vegetation at the
very edge of the pond; this predator only lives in pond B.
e. Individuals in pond B have shorter life spans than individuals in pond A.
The University of Toronto National Biology Competition
2000 Examination
Answer Key
1. d 2. a 3. c 4. e 5. d
6. b 7. b 8. a 9. c 10. e
11. c 12. e 13. a 14. e 15. b
16. e 17. d 18. a 19. e 20. c
21. c 22. d 23. e 24. e 25. b
26. b 27. c 28. e 29. d 30. a
31. b 32. a 33. e 34. d 35. c
36. a 37. c 38. d 39. b 40. d
41. d 42. d 43. b 44. b 45. d
46. e 47. a 48. c 49. a 50. b
The University of TorontoNational Biology Competition
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Should you guess the answers to questions about which you are not certain?
Since your score on the exam is based on the number of questions you answered correctly minus one-third of the number you answered incorrectly, it is improbable that guessing will improve your score (it is more likely to lower your score). (No points are deducted or awarded for unanswered questions.) However, if you are not sure of the correct answer but have some knowledge of the
question and are able to eliminate one or more of the answer choices, then your chance of getting the right answer is improved, and it may be advantageous to answer such a question.
1. Under the electron microscope, you observe a cell with three different types of large organelles, each bounded by two membranes. The cell is most likely to be from:
a. a plant.
b. an animal.
c. a fungus.
d. a bacterium.
e. a virus.
2. In a biology lab exam, a student is given two cultures of single-celled, colourless organisms. She is told that one culture is of an organism collected from the Pacific Ocean and one is of an organism collected from Lake Winnipeg, but neither culture is identified. A question on the exam asks the student to determine which organism came from which source. Which experiment would best provide the answer to the exam question?
a. Look to see which cells had flagella; the flagellated cells were from Lake
Winnipeg.
b. Put some cells of each culture into a 3 M sucrose solution; the cells that shrank
were from the Pacific Ocean.
c. Put some cells of each culture into a 3 M sucrose solution; the cells that shrank
were from Lake Winnipeg.
d. Put some cells of each culture into distilled water; the cells that burst were
from the Pacific Ocean.
e. Put some cells of each culture into distilled water; the cells that burst were
from Lake Winnipeg.
3. From left to right, identify the class of compounds most likely to contain the functional groups shown below.
a. Ketones, aldehydes, carboxylic acids
b. Aldehydes, ketones, carboxylic acids
c. Carboxylic acids, ketones, aldehydes
d. Aldehydes, carboxylic acids, ketones
e. Ketones, carboxylic acids, aldehydes
4. Which statement about macromolecules is FALSE?
a. Monomers are the building blocks of polymers.
b. Both DNA and RNA are linear polymers of nucleotides.
c. A monosaccharide is a long-chain polymer formed of simple sugars.
d. Both cellulose and starch are polymers of glucose.
e. Triglycerides (or simple lipids) contain fatty acids and glycerol.
5. The diagram below shows a polypeptide chain and two adjacent cysteine groups. Which statement is FALSE?
a. The sulfhydryl groups on two cysteine side chains in a protein can react to
form a covalent disulfide bridge.
b. When a cysteine residue is not part of a disulfide bridge, the side chain is
hydrophobic.
c. Loss of hydrogen atoms from sulfhydryl groups of cysteine side chains in a
protein results in a covalent bond that helps stabilize the proteins three-
dimensional structure.
d. The methylene groups on two adjacent cysteine side chains in a protein can
react to form hydrogen bonds that help determine how the protein folds.
e. The cysteine side chains are part of the protein's primary structure, which is
determined by the precise sequence of amino acids in the unbranched
polypeptide chain.
6. A scientist put some photosynthetic plant cells in a solution of inorganic minerals in the dark. He notices that after a few days, the cells could take up mineral A, but not mineral B. Control cells in the same nutrient solution but in the light continued to be able to take up both minerals. Which statement is the best conclusion from all of these observations?
a. Photosynthesis uses light energy to directly transport minerals across the
plasma membrane.
b. Mitochondria do not function in the dark.
c. Mineral A is taken up by diffusion and mineral B by endocytosis.
d. Mineral A is taken up by passive transport and mineral B by active transport.
e. Mineral A is taken up by active transport and mineral B by passive transport.
7. Of the five properties listed below, which are the most important in relation to the function of the plasma membrane in living cells?
i. Selective permeability
ii. Strength
iii. Elasticity
iv. Hydrophilicity
v. Fluidity
a. i and ii
b. i and v
c. ii and iii
d. iii and iv
e. iv and v
8. The graph below shows the titration of acetic acid (CH3COOH). Which statement is FALSE?
a. At the midpoint, [CH3COOH] = [CH3COO-].
b. At the midpoint, pH is about 4.8.
c. At the endpoint, all of the molecules of acetic acid have been titrated to the
conjugate base, acetate.
d. The buffering range of acetic acid is between about pH 4.2 and pH 6.2.
e. The buffering capacity is most effective at pH values below 4 and above 6.
9. Which statement is FALSE?
a. The Golgi complex forms vesicles that fuse to form the endoplasmic reticulum.
b. Cell walls generally contain high levels of carbohydrate.
c. If a lysosome bursts, its contents can seriously damage the cytoplasm of a cell.
d. Secreted proteins are initially formed by ribosomes attached to the
endoplasmic reticulum.
e. The nucleolus is where ribosomes are assembled.
10. Which of the following is NOT a function of glycolysis?
a. Production of ATP.
b. Production of NADH.
c. Production of FADH2.
d. Formation of pyruvate.
e. Splitting the carbon skeletons of simple sugars.
11. The chemiosmotic hypothesis attempts to explain:
a. the movement of water into the chloroplast and its use in photosynthesis.
b. the coupling of ATP formation to electron flow in an electron-transport chain.
c. the movement of lipid-soluble molecules through a membrane.
d. the movement of NADH from the cytoplasm into the mitochondrion.
e. the coupling of chemical gradients to osmosis.
12. The graph below shows two hypothetical reactions: reaction course A represents a reaction uncatalysed by an enzyme, whereas B represents an enzyme-catalysed reaction. Which statement is FALSE?
a. When an enzyme changes the activation energy of a reversible reaction of the
type x y, both
the forward and reverse reactions speed up.
b. The uncatalysed reaction (A) requires a higher activation energy than does the
enzyme-catalysed reaction (B).
c. The change in free energy is the same for both reactions.
d. Adding an enzyme to mediate a reaction (B) does not alter the difference in
free energy between the reactants and products; it only changes the activation
energy and hence the rate constant.
e. Both reactions proceed to equilibrium at the same rate.
13. Which one of the following is an end product of the Calvin cycle, the dark reaction of photosynthesis?
a. ATP
b. NADPH
c. A three-carbon sugar
d. Oxygen
e. Carbon dioxide
14. Some human cells divide approximately every 24 hours. You do some experiments to show that the G1 and S phases take up half of the cycle time. Further microscopic observations demonstrate that the mitotic phase is one hour long. How long does the post-synthesis "gap" take in this case?
a. 1 hour
b. 6 hours
c. 9 hours
d. 11 hours
e. 23 hours
15. If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be stopped?
a. Anaphase
b. Prophase
c. Telophase
d. Interphase
e. Metaphase
16. Albinism (lack of skin pigmentation) is caused by a recessive autosomal allele. A man and a woman, both normal pigmented, have an albino child together. The couple then have a second child. What is the probability that the second child will be albino?
a. 0
b. 25%
c. 50%
d. 75%
e. 100%
17. All of the following are used as evidence that genes are on chromosomes EXCEPT:
a. The structure of DNA is a polymer of nitrogenous bases linked together by a
"backbone" of alternating phosphates and sugars.
b. The correlation of the Mendelian law of segregation with the segregation of
chromosomes in meiosis.
c. The correlation of the Mendelian law of independent assortment with the
assortment of chromosomes in miosis.
d. The correlation of Down's syndrome in humans with an extra chromosome 21.
e. The sex linked inheritance of some forms of colour blindness in human males
correlates with the inheritance of one X and one Y chromosome in males.
18. The relationship between genotype and phenotype is rarely simple. The term "pleiotropy" describes:
a. when a heterozygote individual has a phenotype intermediate between those of
the two types of homozygotes.
b. when a heterozygote exhibits phenotypes for both its alleles.
c. the ability of a single gene to affect multiple phenotypic traits.
d. when one gene affects the expression of another gene.
e. characters that vary continuously, indicating an additive effect of two or more
genes on a single phenotypic character.
19. Which statement about meiosis is FALSE?
a. The two meiotic divisions reduce the DNA content per cell to one half of the
initial content.
b. Crossing over occurs in prophase of the second meiotic division.
c. In many species, the haploid products of meiosis proliferate by mitotic
division.
d. In many multicellular organisms only one of the four products of meiosis is
inherited.
e. There is no DNA replication between the first and second meiotic division.
20. Gene therapy for deleterious mutations in blood cells is becoming possible by introducing normal genes into blood cell precursors in the laboratory and re-injecting these cells into the patient. Which of the following would NOT be associated with this kind of gene therapy research?
a. Attempting to place the normal gene in a vector which will help the gene
integrate into a chromosome.
b. Utilising virus vectors which have had some of their own genes removed.
c. Utilising a suitably modified HIV virus.
d. Preventing transmission of the mutation to the next generation.
e. Finding gene transfer methods for treating other genetic disorders, such as
cystic fibrosis.
21. If 35% of the bases of a DNA molecule are thymine, it follows that it also contains:
a. 30% adenine.
b. 30% cytosine.
c. 15% guanine.
d. 35% uracil.
e. None of the above are correct.
22. Molecular biologists cracked the code of life in the 1960s, when a series of elaborate experiments disclosed the amino acid translations of each of the mRNA codons. How many triplet mRNA codons are there?
a. 16
b. 20
c. 32
d. 64
e. As many as there are amino acids, plus the initiation and termination codons.
23. You are asked to generate, within two weeks, a collection of recombinant plasmid clones that contain pieces of a large proportion of all human genes. What would be the fastest strategy?
a. Digest human DNA with a restriction enzyme; digest the plasmid with two
further restriction enzymes. Ligate the human and plasmid DNA and transfer
DNA to bacteria.
b. Digest human and plasmid DNA with the same restriction enzyme. Ligate the
human and plasmid DNA and transfer DNA to bacteria.
c. Digest human DNA extensively with a conventional endonuclease; digest the
plasmid with a restriction enzyme producing "blunt ends." Ligate the human and
plasmid DNA and transfer DNA to bacteria.
d. Transform human DNA to bacteria which contain a plasmid. Use a bacterial
recombination system to integrate this DNA into the plasmids.
e. This cannot be done in two weeks or less.
24. The term "translation" refers to:
a. the excision and reintegration of a DNA fragment.
b. a specific type of DNA repair.
c. the synthesis of a polypeptide according to an RNA sequence.
d. the synthesis of RNA according to a DNA sequence.
e. the synthesis of DNA according to an RNA sequence.
25. A population is in genetic equilibrium when genotype and allele frequencies remain the same from one generation to the next. Genetic equilibrium will occur when:
a. populations are small, thus more likely to be affected by genetic drift.
b. beneficial mutations arise.
c. there is no immigration and emigration.
d. there is mating between close relatives.
e. natural selection is acting on a particular phenotype.
26. In a population of diploid individuals that is in Hardy-Weinberg equilibrium, the frequency of a dominant allele for a certain hereditary trait is 0.3. What percentage of individuals in the next generation would be expected to be homozygous for the dominant trait?
a. 9%
b. 14%
c. 42%
d. 49%
e. 90%
27. When Shakespeare was alive cobs of maize (corn) grew to about 15 cm in length, whereas today they can be almost twice this size. This is because:
a.. of the cooler temperatures and decreased rainfall experienced at that time.
b. agricultural fields in England were small at that time and thus nutrients were
limiting.
c. recombinant DNA technology was not being practised at that time.
d. plant breeding using genetic principles was not introduced until the 20th
century.
e. of the lack of genetic variation in maize from Mexico, where maize originated.
28. Many people were sceptical of the theory of evolution when Darwin first proposed it. Darwin received such sharp criticism because:
a. the bones in the wings of bats, fins of porpoises, and legs of humans were
known to be analogous structures.
b. he could not explain completely how evolution occurred because he did not
know the mechanism of inheritance.
c. the fossil record indicated that there were links between birds and reptiles.
d. Earth was thought to be much older than it actually is.
e. he proposed that chimpanzees had evolved into humans.
29. The sequence of events in geographic speciation is most likely to be:
a. Genetic divergence --> geographic barrier --> reproductive isolation.
b. Geographic barrier --> genetic divergence --> reproductive isolation.
c. Reproductive isolation --> genetic divergence --> geographic barrier.
d. Geographic barrier --> reproductive isolation --> genetic divergence.
e. Genetic divergence --> reproductive isolation --> geographic barrier.
30. Elderly people are advised to get influenza (flu) vaccinations every year. Each year, a different type of flu vaccine has to be made. This is because:
a. different viruses attack people of different ages, so each year as the population
ages, a new vaccine must be produced.
b. antibodies to the flu vaccine do not survive very long in the blood.
c. vaccines are unstable and cannot be stored for more than one year.
d. the body learns to destroy the antibodies made against the vaccine, so a new
type of vaccine is needed for each vaccination.
e. flu viruses change their genetic constituents so rapidly that vaccines against
them rapidly become obsolete.
31. Which important aspect of the classification of all organisms is attributed to Carl Linnaeus?
a. The use of Latin.
b. The use of branching diagrams (trees) to depict relationships among groups.
c. The use of two-part names (binomials).
d. The use of standardized common names.
e. The use of keys for identification.
32. It is generally agreed that prokaryotes constituted the first life on Earth. It is also generally accepted that the early eukaryotes were:
a. photosynthetic.
b. chemosynthetic.
c. heterotrophs.
d. multicellular.
e. unicellular.
33. Which group of organisms has the largest number of described species?
a. Arthropods
b. Vertebrates
c. Bacteria
d. Fungi
e. Flowering plants
34. A mycorrhiza is a mutualistic association between a fungus and a plant's roots. Which statement best characterizes this association?
a. The fungus provides nothing to the plant; the plant provides food to the
fungus.
b. The fungus secretes toxins to kill the plant; the plant provides minerals to the
fungus.
c. The fungus provides minerals to the plant; the plant secretes toxins to kill the
fungus.
d. The fungus provides minerals to the plant; the plant provides food to the
fungus.
e. The fungus provides minerals to the plant; the plant provides nothing to the
fungus.
35. Which statement about water movement in plants is FALSE?
a. It occurs from a region of low to high concentration.
b. It occurs in dead cells, called tracheids and vessel elements.
c. It depends on the cohesive properties of molecules.
d. It depends on the adhesive properties of molecules.
e. Water moves from the leaf to the atmosphere by diffusion.
36. It is common practice for farmers to pick tomatoes while they are green and to store them in a warehouse prior to shipment to the local grocery store. Prior to shipment, the tomatoes are treated with a growth regulator to induce ripening. Which growth regulator is used?
a. Cytokinin
b. Auxin
c. Abscisic acid
d. Gibberellin
e. Ethylene
37. In which region of the vertebrate digestive tract does the majority of nutrient absorption into the blood stream occur?
a. Stomach
b. Colon
c. Small intestine
d. Large intestine
e. Esophagus
38. The separation of oxygen from hemoglobin is enhanced near exercising muscle (this is known as the Bohr effect) and is caused by:
a. oxygen binding to hemoglobin in the lung.
b. carbon monoxide binding to oxygenated hemoglobin.
c. carbonic anhydrase.
d. the interaction of lowered pH with oxygenated hemoglobin.
e. the interaction of carbon dioxide with oxygenated hemoglobin.
39. Beginning from the anterior (= superior) vena cava, what is the correct pathway of blood through the mammalian heart? (R = right, L = left)
a. R atrium --> R ventricle --> pulmonary vein --> lung circuit --> pulmonary
artery --> L atrium --> L ventricle --> aorta.
b. L atrium --> L ventricle --> pulmonary artery --> lung circuit --> pulmonary
vein --> R atrium --> R ventricle --> aorta.
c. Aorta --> L atrium --> L ventricle --> pulmonary vein --> lung circuit -->
pulmonary artery --> R ventricle --> R atrium.
d. R ventricle --> R atrium --> pulmonary artery --> lung circuit --> pulmonary
vein --> L atrium --> L ventricle --> aorta.
e. R atrium --> R ventricle --> pulmonary artery --> lung circuit --> pulmonary
vein --> L atrium --> L ventricle --> aorta.
40. Which of the following is a "key event" in the evolution of vertebrates?
a. Gut formation from the coelom
b. Formation of the neural crest
c. Spiral cleavage
d. Gastrulation following cell cleavage
e. Organogenesis to produce organs
41. Oogenesis is the process in the ovary that results in the production of female gametes. Which statement about oogenesis in humans is FALSE?
a. Oogenesis begins before birth.
b. In oogenesis, unequal cytokinesis results in one single large daughter cell,
which goes on to form the egg.
c. At birth, an ovary already contains all the cells it will ever have that will
develop into eggs.
d. The process of oogenesis is completed when the egg cell is penetrated by
sperm.
e. Oogenesis continues throughout the life of the individual.
[see comments]
42. As a nerve impulse passes along an axon:
a. the membrane potential changes from positive to negative and then back again.
b. sodium ions flow out through ion channels and potassium ions flow in.
c. sodium channels open as the membrane potential becomes less negative.
d. the sodium-potassium pump moves sodium ions into the cell.
e. potassium channels close as the membrane potential becomes more positive.
43. A main function of the autonomic nervous system, which consists of the sympathetic and parasympathetic divisions, is to:
a. act as an inhibitory system for skeletal muscle.
b. control the activity of a variety of secretory cells throughout the body.
c. communicate between the two halves of the brain.
d. control involuntary reflexes such as the knee-jerk response.
44. Some athletes take "steroids" in an attempt to enhance their physical performance. This can lead to decreased sperm production and even sterility. What is the most likely explanation for this effect?
a. Interference in the proper negative feedback control of testosterone by
luteinizing hormone.
b. Increased stimulation of the anterior pituitary to produce luteinizing hormone.
c. Excessive growth of testicular tissue.
d. Suppression of the natural production of thyroxin due to the destruction of
thyroid tissue.
e. Excessive diversion of protein and other metabolites from the gonads to
muscle tissue.
45. If you were outside for a long time on a hot, dry day, without anything to drink, which of the following would happen?
a. The production of thyroxin by your thyroid gland would increase.
b. The osmotic pressure of your blood would decrease.
c. The re-absorption of fluids from your kidney tubules would decrease.
d. The concentration of urea in your urine would decrease.
e. The secretion of anti-diuretic hormone from your pituitary gland would
increase.
46. In which ecosystem would you find the highest biodiversity?
a. Freshwater marsh
b. Prairie grassland
c. Tundra
d. Boreal forest
e. Cultivated field
47. The diagram below shows the feeding interactions between nine species (A to I) of a food web with four trophic levels. Which statement about this food web is CORRECT?
a. Species A is a herbivore.
b. Species D is a carnivore.
c. Species G is an omnivore.
d. Species H is a predator.
e. Species I is a primary producer.
48. What is the "carrying capacity" of a population?
a. The rate at which the density of individuals increases over time.
b. The maximum number of individuals which can be supported in a given
environment.
c. The proportion of individuals which are most responsible for population
growth.
d. The minimum number of individuals necessary to avoid extinction of the
population.
e. The number of individuals available to support higher trophic levels.
49. Which of the following is NOT a major cause of species extinction today?
a.. Introduction of diseases
b. Global climate change
c. Hunting
d. Habitat destruction
e. Introduction of predators
50. An experiment was conducted to determine the feeding preference of guppies. Four treatments were conducted where
guppies were offered different mixtures of worms and flies: from a mixture of 20% worms (and 80% flies) to a mixture of 80% worms (and 20% flies). The stomach contents of the guppies were compared to determine what they actually ingested. The results are shown below (circles = mean values, vertical bars = total ranges). What can be concluded from these results?
a. Guppies prefer worms.
b. Guppies prefer flies.
c. Guppies prefer the least abundant food available.
d. Guppies prefer the most abundant food available.
e. Guppies do not have a feeding preference.
The University of Toronto National Biology Competition
The University of Toronto National Biology Competition
1998 Examination Time: 90 minutes
Number of Questions: 60
NOTE:
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Indicate all of your answers to the questions on the separate Response Form. No credit
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After you have decided which of the suggested answers is best, COMPLETELY fill in the
corresponding bubble on the Response Form. Give only one answer to each question. If
you change an answer, be sure that the previous mark is erased completely.
Use your time effectively. Do not spend too much time on questions that are too difficult.
Go on to other questions and come back to the difficult ones later if you have time. It is
not expected that everyone will be able to answer all questions.
Good luck and have fun!
Should you guess the answers to questions about
which you are not certain?
Since your score on the exam is based on the number of questions you answered correctly minus one-third of the number you answered incorrectly, it is improbable that guessing will improve your score (it is more likely to lower your score). (No points are deducted or awarded for unanswered questions.) However, if you are not sure of the correct answer but have some knowledge of the question and are able to eliminate one or more of the answer choices, then your chance of getting the right answer is improved, and it may be advantageous to answer such a question.
1. Which statement best describes the process of endocytosis?
a. A vesicle within a cell fuses with the plasma membrane and releases its
contents to the outside.
b. Solid particles or liquids are taken up by a cell through invagination of the
plasma membrane.
c. Investment in one cytosis reduces the ability of the parent to assist another
cytosis.
d. One region of an embryo directs the development of a neighbouring region of
an embryo through movement of cells.
e. An organism obtains its energy from light and organic compounds.
2. The primary role of a lysosome is:
a. intracellular digestion.
b. ATP synthesis.
c. lipid transport.
d. carbohydrate storage.
e. protein synthesis.
3. Which statement about chloroplasts is FALSE?
a. They are organelles with a double membrane.
b. They contain their own genetic information and ribosomes.
c. They are found in eukaryotic and prokaryotic cells.
d. The thylakoid membranes within the chloroplast contain chlorophyll.
e. They contain ATP.
4. The graphs below show the relationship between the rate of water loss by transpiration and leaf
temperature. Based on these results, which plant is best adapted for conserving water in a hot dry
environment?
a. Sunflower
b. Maple
c. Creosote
d. Grass
e. Pine
5. Which statement about microtubules is FALSE?
a. They form the spindle fibres involved in movement of chromosomes during
mitosis and meiosis.
b. They are involved in cell support and shape.
c. They are involved in the movement of flagella.
d. They are involved in the movement of cilia.
e. They are made up of carbohydrate molecules called phospholipids.
6. Which structure is present in a bean sprout (young seedling), but not in a bean seed?
a. Elongated hypocotyl
b. Radicle
c. Two cotyledons
d. Endosperm
e. Micropyle
7. Plant hormones play a role in regulating the development of plant seeds. The graphs below plot
embryo growth and the changes in hormone concentration over time. Based on these results,
which hormone(s) most likely regulate(s) embryo growth?
a. Auxin alone
b. Gibberellic acid alone
c. Abscisic acid alone
d. Both auxin and gibberellic acid
e. Both auxin and abscisic acid
8. Cell division typically occurs only in the meristematic regions of plants. In which region would
cell division NOT occur?
a. Shoot apex
b. Wood
c. Root apex
d. Cambium between wood and bark
e. Expanding leaf
9. How many times does cytokinesis occur during the entire process of meiosis?
a. 1
b. 2
c. 3
d. 4
e. 5
10. In humans, the sex ratio is very close to 50:50. The best genetic explanation for this is:
a. crossing over.
b. independent assortment.
c. linkage.
d. transformation.
e. segregation.
11. There are three alleles at the ABO antigen locus in humans. The A and B alleles produce A and
B antigens, respectively, while the O allele produces no antigen. For which of the following
phenotypes could you be certain that an individual (with that phenotype) is a homozygote?
a. Type A only
b. Type B only
c. Type O only
d. Types A, B, and O
e. None of the phenotypes
12. Quebec premier Lucien Bouchard had his leg amputated because of an infection known as the
"flesh-eating disease." This disease seems to have become a problem in Canada because of:
a. recent contact between humans and rodents.
b. travel between Africa and Canada.
c. the transmission of a virus from chickens to humans.
d. the evolution of antibiotic resistance.
e. contaminated hamburgers at fast food chains.
13. Which of the following would NOT be found in the cell of a bacterium?
a. DNA
b. Ribosomes
c. Plasma membrane
d. Pili
e. Mitochondria
14. Which statement is FALSE?
a. Bacteria are necessary for decomposition.
b. Bacteria can cause diseases of plants.
c. Bacteria are part of your "personal" microflora.
d. Bacteria are necessary for biological nitrogen fixation.
e. Bacteria are necessary for photosynthesis.
15. In Canada, recent outbreaks of meningitis, caused by a virus, were controlled by immunization
with a vaccine. Unfortunately, AIDS caused by the HIV virus has not yet been controlled by a
vaccine because of the:
a. cost of development and production of vaccines.
b. availability of effective antibiotics.
c. high degree of variability in the HIV virus.
d. complex structure of the HIV virus.
e. lack of antigenic proteins on the HIV virus.
16. Which statement is CORRECT?
a. Appendicitis can lead to the condition known as peritonitis, in which parts of
the liver are destroyed.
b. Heartburn is caused by the acidic contents of the stomach escaping into the
thoracic cavity.
c. Hepatitis is a condition where there are insufficient bile salts to dissolve
cholesterol; the cholesterol then forms large crystals.
d. Hiatal hernia is a condition in which part of the stomach may protrude through
the diaphragm into the thoracic cavity.
e. Gallstones are mainly composed of uric acid and can often be treated with
ultrasound.
17. In herbivorous mammals, the cellulose of plant cell walls:
a. is digested by enzymes produced by symbiotic microorganisms.
b. is digested by cellulase, which is secreted by the lining of the rumen.
c. is hydrolysed to simple molecules by large quantities of saliva.
d. cannot be digested and therefore forms the bulk of the faeces.
e. cannot be digested, but the cell walls are broken down by the mechanical
action of the teeth so that the cell contents are released and become available.
18. Which statement about gas exchange in vertebrates is FALSE?
a. Most of the carbon dioxide in the blood is carried in the form of bicarbonate
ions.
b. Without diffusion, there would be no gas exchange.
c. If the concentration of carbon dioxide in the alveolar air increases, the rate of
carbon dioxide exchange decreases.
d. Less carbon dioxide would be carried by the blood if there were fewer red
blood cells.
e. An increase in oxygen concentration would result in less oxygen binding to the
iron atoms in haemoglobin.
19. The trachea, bronchi, and bronchioles of humans have all of the following functions
EXCEPT:
a. increasing the surface area available for gas exchange.
b. moistening the incoming air.
c. conducting mucous away from the alveoli.
d. warming the incoming air to body temperature.
e. conducting air from the exterior of the body to where the respiratory gases can
enter or leave the blood.
20. Which statement is FALSE?
a. Veins are typically larger in diameter than arteries.
b. Because of their small size, capillaries contain blood that is moving more
quickly than in other parts of the circulatory system.
c. The walls of arteries are elastic, enabling them to stretch and shrink with
changes in blood pressure.
d. Veins contain more blood than any other part of the circulatory system.
e. The blood pressure in the veins is normally too low for blood to return to the
heart without the action of skeletal muscles.
21. Some of the important events in the human female reproductive cycle are listed below. Which
of the following best describes their sequence?
1 - A drop in progesterone levels
2 - Secretion of follicle stimulating hormone
3 - Growth of the corpus luteum
4 - Oogenesis
5 - Menstruation
6 - Ovulation
7 - Growth of the follicle
8 - A sudden increase in levels of luteinizing hormone
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Answer Key
General Instructions
Do not open this booklet until you are instructed to do so.
Print your name at the top of this booklet.
Indicate all of your answers to the questions on the separate Response Form. No credit
will be given for anything written in this booklet, but you may use the booklet for notes or
rough work. No additional time will be given after the exam to transfer your answers to
the Response Form.
After you have decided which of the suggested answers is best, COMPLETELY fill in the
corresponding circle on the Response Form. Give only one answer to each question. If
you change an answer, be sure that the previous mark is erased completely.
Use your time effectively. Do not spend too much time on questions that are too difficult.
Go on to other questions and come back to the difficult ones later if you have time. It is
not expected that everyone will be able to answer all questions.
Since your score on the exam is based on the number of questions you answered correctly minus one-third of the number you answered incorrectly, it is improbable that guessing will improve your score (it is more likely to lower your score). (No points are deducted or awarded for unanswered questions). However, if you are not sure of the correct answer but have some knowledge of the question and are able to eliminate one or more of the answer choices, then your chance of getting the right answer is improved, and it may be advantageous to answer such a question.
1. Which statement is FALSE?
a. A ribosome is smaller than a centriole.
b. The nucleus has one membrane surrounding it.
c. Plant cells contain mitochondria.
d. A centriole contains microtubules.
e. The largest organelle in a typical plant cell is the vacuole.
[The Answer is...]
2. A scientist put some plant cells in a solution of glucose and, after 30 minutes, measured the
concentration of glucose inside the cells. When she repeated the experiment using double the
concentration of glucose in the solution, the concentration of glucose inside the cells also doubled.
Which of the following principles does this experiment demonstrate?
a. Glucose enters plant cells by active transport.
b. Glucose enters plant cells by endocytosis.
c. Glucose enters plant cells by some type of diffusion.
d. Plant cells cannot synthesize glucose.
e. Glucose moves into plant cells by osmosis.
[The Answer is...]
3. Which statement best explains why protozoans that live in pond water must use exocytosis to
get rid of excess water in their cytoplasm?
a. The pond water is hypotonic to the protozoan cytoplasm.
b. The pond water is hypertonic to the protozoan cytoplasm.
c. The pond water is isotonic to the protozoan cytoplasm.
d. Water cannot diffuse across the protozoan plasma membrane.
e. Protozoans take up water by endocytosis; therefore, they must expel it by
exocytosis.
[The Answer is...]
4. Plant cells can often grow larger than animal cells because:
a. photosynthesis produces more energy than does respiration.
b. plant cells need less food than animal cells.
c. plants use their energy for growth while animals spend much of their energy
on movement.
d. plant cells have a cell wall which makes their surface to volume ratio very
large.
e. the large central vacuole of plant cells reduces the depth of the cytoplasm and
allows entering molecules to rapidly diffuse from the plasma membrane to all
parts of the cytoplasm.
[The Answer is...]
5. Which of the following cell types provide mechanical support for plants?
a. Tracheids, sclerenchyma fibres, collenchyma
b. Sclerenchyma fibres, cork, cortex
c. Sieve tubes, vessel elements, epidermis
d. Sclerenchyma fibres, pith cells, epithelial cells
e. Pith, cortex, xylem
[The Answer is...]
6. Water can move from the soil and up through the world's tallest living tree (which is 110 metres
high) by which of the following process(es)?
a. Osmosis
b. Root pressure
c. Pressure flow
d. Adhesion and cohesion of water molecules
e. All of the above
[The Answer is...]
7. Which statement about the function of the Casparian strip is CORRECT?
a. It prevents excess transpiration from leaves.
b. It regulates ion movement into the root vascular cylinder.
c. It prevents disease organisms from invading the plant.
d. It prevents ions from leaking out of the xylem into leaves.
e. It is the pathway for nutrient transfer from xylem to phloem.
[The Answer is...]
8. What path does a carbon atom take in going from the atmosphere into the cell wall of a root cap
cell?
a. Stoma---proplastid---chloroplast---vessel element---procambium---apical
meristem---root cap
b. Stoma---chloroplast---phloem---apical meristem---procambium---root cap
c. Stoma---chloroplast---vessel element---procambium---apical meristem---root
cap
d. Stoma---chloroplast---sieve tube---procambium---apical meristem---root cap
e. All of these paths are possible.
[The Answer is...]
9. The plant growth regulator involved in aging and ripening of fruit is:
a. cytokinin.
b. auxin.
c. gibberellin.
d. abscisic acid.
e. ethylene.
[The Answer is...]
10. Which of the following provides the best evidence that all known forms of life descended from
a common ancestor?
a. DNA
b. Chloroplasts
c. The genetic code
d. The homeobox sequence
e. Mitochondria
[The Answer is...]
11. Two cells which are exactly like the original cell result from:
a. gamete formation.
b. meiosis.
c. mitosis.
d. sexual reproduction.
e. syngamy.
[The Answer is...]
12. Imagine that in a plant, hairy leaves are dominant to smooth leaves, and blue flowers are
dominant to white. You cross a pure breeding hairy-leaved, blue-flowered strain with a pure
breeding smooth-leaved, white-flowered strain. You allow the offspring to self-fertilize, and
observe that the F2 offspring are 69% hairy-leaved and blue-flowered, 19% smooth-leaved and
white-flowered, 6% hairy-leaved and white-flowered, and 6% smooth-leaved and blue-flowered.
Based on these observations you can conclude that the two genes:
a. are in the same biochemical pathway.
b. segregate independently.
c. exhibit typical Mendelian ratios.
d. are on the same chromosome.
e. show epistatic interactions.
[The Answer is...]
13. Recently, scientists induced a single diploid cell from an adult sheep (the "mother") to grow
into a lamb, named Dolly. How closely are Dolly and her "mother" related?
a. They are completely unrelated.
b. They are about as related as a brother and a sister would be.
c. They are about as related as fraternal twins.
d. They are about as related as identical twins.
e. They are completely identical genetically.
[The Answer is...]
14. You are moving to Africa and you have heard that the Green Fever virus disease is common
there. Before you leave, you visit your doctor for advice. Which of the following is your doctor
most likely to recommend? You should:
a. take a large supply of antibiotics with you.
b. wash your food in an antiseptic before you eat it.
c. get vaccinated against the disease.
d. not worry as viruses only cause diseases in plants.
e. get regular blood tests which will use the light microscope to look for virus
particles.
[The Answer is...]
15. A hospital technician, while doing some routine culturing of micro-organisms in a lab, noticed
a bacterial colony growing on a culture medium containing three different antibiotics. He
identified the bacterium as one that did not cause a human disease, but he still reported his
observation to the hospital administration. Which statement is CORRECT? He was worried
because:
a. he had no way of killing this bacterium now that it was resistant to antibiotics.
b. resistance to antibiotics could be transferred to disease-causing bacteria by
transduction or conjugation.
c. the bacterium might feed on the antibiotics and therefore be able to grow in
people taking these antibiotics.
d. there should be no bacteria inside a hospital.
e. if people accidentally ingested the bacteria with their food, they would become
resistant to the antibiotic.
[The Answer is...]
16. Which statement is FALSE?
a. Viruses primarily contain nucleic acids and protein.
b. All viruses are parasites.
c. Bacteria are usually less than 2 micrometres in diameter.
d. Autotrophic bacteria can use carbon dioxide as their sole source of carbon.
e. Bacteria can only fix nitrogen when they are inside the root nodules of
leguminous plants, such as peas and beans.
[The Answer is...]
17. Which statement is FALSE?
a. Pepsin is an enzyme that acts on peptide chains to digest proteins.
b. The enzyme enterokinase produces the protein-digesting enzyme trypsin from
trypsinogen.
c. The bile helps digestion by breaking fat into tiny droplets.
d. The pancreas produces more than 20 different digestive enzymes.
e. Salivary amylase starts the process of protein digestion in the mouth.
[The Answer is...]
18. Which of the following best represents the path taken by an amino acid molecule after it is
ingested?
a. mouth---salivary glands---oesophagus---small intestine---pancreas
b. mouth---oesophagus---stomach---duodenum---liver
c. mouth---duodenum---stomach---small intestine---colon
d. mouth---oesophagus---pancreas---jejunum---stomach
e. mouth---jejunum---liver---colon---small intestine
[The Answer is...]
19. Which of the following statements about the gills of fish is FALSE?
a. The flow of water over the gill is in the same direction as the flow of blood in
the filament.
b. Oxygen gas dissolved in the water diffuses into blood vessels of the gill.
c. Blood flows into and out of each filament of the gill in separate vessels.
d. Decreasing the rate of movement of water over the gills would decrease
oxygen uptake.
e. Most fish actively force water over their gills by movement of the operculum.
[The Answer is...]
20. In a mammalian lung the rate at which oxygen could be obtained from the air would increase
if:
a. tidal volume decreased.
b. the cells lining the alveoli and capillaries were thinner.
c. blood haemoglobin content were lower.
d. you ascended to a higher altitude.
e. the alveoli were larger.
[The Answer is...]
21. Which statement is FALSE?
a. Capillaries in muscle are usually empty of blood.
b. The mammalian heart will continue to beat when its nerve supply is cut.
c. In vertebrates, veins can be distinguished from arteries because veins carry
deoxygenated blood.
d. Water and small molecules can easily pass through the walls of most
capillaries.
e. Circulation of blood in the coronary arteries is greatest during diastole, when
the heart is filling.
[The Answer is...]
22. If a molecule of carbon dioxide released into the blood in the foot of a human foetus is exhaled
through the mouth of the mother, it will NOT travel through the:
a. right atrium of the foetus.
b. right atrium of the mother.
c. left ventricle of the foetus.
d. left ventricle of the mother.
e. placenta.
[The Answer is...]
23. Which statement is FALSE?
a. Cell division to form a blastocyst begins after the fertilized egg is implanted in
the endometrium of the uterus.
b. The placenta contains cells derived both from the embryo and the mother.
c. Follicle stimulating hormone (FSH) stimulates the production of sperm in the
male testes.
d. Human males can continue to produce sperm throughout life, whereas females
stop producing eggs during menopause.
e. Some female mammals only release eggs from their ovaries when copulation
occurs.
[The Answer is...]
24. Trace a sperm cell from the structure where it is produced to fertilization of the egg:
Since your score on the exam is based on the number of questions you answered correctly minus one-third of the number you answered incorrectly, it is improbable that guessing will improve your score (it is more likely to lower your score). (No points are deducted or awarded for unanswered questions). However, if you are not sure of the correct answer but have some knowledge of the question and are able to eliminate one or more of the answer choices, then your chance of getting the right answer is improved, and it may be advantageous to answer such a question.
1. All cells have:
a. a cell wall and nucleus.
b. a nucleus and chloroplasts.
c. plastids and lysosomes.
d. a cell membrane and cytoplasm.
e. ribosomes and chloroplasts.
[The correct answer is...]
2. A scientist added a chemical (cyanide) to an animal cell to stop aerobic respiration. Which of
the following is most likely to have been affected by this treatment?
a. Active transport of substances across the plasma membrane
b. Passive transport of substances across the plasma membrane
c. Diffusion of substances across the plasma membrane
d. The size of the ribosomes in the cytoplasm
e. The thickness of lipid bilayers
[The correct answer is...]
3. Which statement is FALSE?
a. If a lysosome bursts, its contents can seriously damage the cytoplasm of a cell.
b. Chloroplasts and mitochondria are each bounded by two membranes.
c. Macromolecules may be taken up into a cell by the process of endocytosis.
7. Deep-water rice is an important crop in southeast Asia where water levels during the rainy season may rise by several metres within a short time. Deep-water rice has the ability to adapt to the rising water by growing quickly, thus keeping its "head" (flower stalk and upper leaves) above water. Examine the four graphs above and identify the hormone(s) that regulate(s) this rapid growth.
a. Ethylene alone
b. Cytokinin alone
c. Gibberellin alone
d. Ethylene and gibberellin
e. Cytokinin and gibberellin
[The correct answer is...]
8. Cactus plants are adapted to the hot and dry deserts of North and South America. Which of the
following characteristics would NOT help cacti to survive the extreme heat and low rainfall?
sink (such as a developing fruit where they are used or stored). Which of the following statements
about phloem transport is FALSE?
a. Water enters the sieve tubes by osmosis.
b. Sieve tubes in a source have a low hydrostatic pressure.
c. Water and solutes move through the sieve tubes along a pressure gradient.
d. Solutes are actively removed from the sieve tubes in the sink area.
e. Solutes are swept along by the bulk flow of water in the sieve tubes.
[The correct answer is...]
38. Using the four graphs above and your knowledge of the action spectrum of photosynthesis and the absorption spectra of chlorophyll a and chlorophyll b, identify the plant pigment responsible for phototropism.
39. Which of the following gives sexual reproduction an advantage over asexual reproduction?
a. It produces more offspring.
b. It ensures the survival of the species.
c. It increases the variation among the offspring of an individual.
d. It preserves parental genotypes.
e. It allows evolution due to sexual selection.
[The correct answer is...]
40. Typically, plant species are adapted for photosynthesis in a specific temperature range. Examine the above graph that shows the relationships between photosynthetic rate and temperature for the following species: alpine tussock grass (a C3 species); wheat from the temperate zone (C3); maize from the subtropics (C4). Which statement about these relationships is FALSE?
a. Wheat is the species that has the highest rate of photosynthesis when
temperatures are around 25°C.
b. Maize shows maximum photosynthetic rates at 38°C.
c. Wheat shows maximum photosynthetic rates at 25°C.
d. In a region where mean temperatures were 10°C, C3 species would have
higher photosynthetic rates than C4 species.
e. In the arctic tundra where mean daily temperatures might be as low as 0°C, the
C3 tussock grass would have the highest rate of photosynthesis.
[The correct answer is...]
41. Normally, genetic information is passed from DNA to RNA to protein. Which recently
discovered process can pass information in the other direction?
size has crashed. Here is simple model of a fishery:
H = N x E x G
H = harvest size (number of fish caught)N = total population size (number of fish)E = the harvest effort (the number of days spent fishing times the number of boats fishing; in other words, the units of E are boat-days)G = efficiency (the proportion of N caught per boat per day)Which management approach is most sustainable and will NOT cause the population to crash in the long run?
a. As N decreases, increase G by using either sonar to find the fish more easily,
nets with smaller mesh sizes, or other advances in technology.
b. As N decreases, increase E by allowing more boats to fish or more days of
fishing.
c. As N decreases, increase H.
d. As N decreases, set a level for H and keep it fixed at that level.
e. As N decreases, either E or G can change, but their product must remain
constant.
[The correct answer is...]
59. We have introduced an animal species to an island where it undergoes exponential growth in
this new unexploited, resource-rich environment. The initial population size (year 0) is 20
individuals (point shown on graphs). After 4 years the population size is 80 individuals. What is
the population size after 10 years, assuming that exponential growth has continued?
a. The population will be at its carrying capacity, but too little information about
the biology of the species is given to determine what that value is.
(this was unintentional); response (a) of question 36 had a typographical error
(O6, not O26) in the original version of the test which made this response correct,
in addition to response (e).
The University of Toronto Ontario Biology Competition
1995 Examination Time: 90 minutes
Number of Questions: 60
Answer Key
General Instructions
Do not open this booklet until you are instructed to do so.
Print your name at the top of this booklet.
Indicate all of your answers to the questions on the separate Response Form. No credit
will be given for anything written in this booklet, but you may use the booklet for notes or
rough work. No additional time will be given after the exam to transfer your answers to
the Response Form.
After you have decided which of the suggested answers is best, COMPLETELY fill in the
corresponding circle on the Response Form. Give only one answer to each question. If
you change an answer, be sure that the previous mark is erased completely.
Use your time effectively. Do not spend too much time on questions that are too difficult.
Go on to other questions and come back to the difficult ones later if you have time. It is
not expected that everyone will be able to answer all questions.
Good luck and have fun!
Should you guess the answers to questions about
which you are not certain?
Since your score on the exam is based on the number of questions you answered correctly minus one-fourth of the number you answered incorrectly, it is improbable that guessing will improve
your score (it is more likely to lower your score). (No points are deducted or awarded for unanswered questions). However, if you are not sure of the correct answer but have some knowledge of the question and are able to eliminate one or more of the answer choices, then your chance of getting the right answer is improved, and it may be advantageous to answer such a question.
1. If a plant cell has its cell wall removed and is placed in a hypotonic solution, what will happen to the cell?
a. The cell will already be dead because plant cells cannot survive without a cell
wall.
b. The cell will expand and eventually burst.
c. The cell will shrink because the vacuole gets smaller.
d. Nothing obvious would happen.
e. The nucleus will burst, but the cell will stay intact.
[The correct answer is...]
2. Under a light microscope, tiny dots can be seen in the cytoplasm of living plant and animal
cells. These are likely to be:
a. chloroplasts.
b. ribosomes.
c. mitochondria.
d. nuclei.
e. chromosomes.
[The correct answer is...]
3. Which statement is FALSE?
a. During the process of exocytosis, the lumen (inner) surface of a secretory
vesicle becomes the inside of the plasma (cell) membrane.
b. Cilia, microtubules, and flagella are all associated with movement in cells.
c. A function of the nucleus is duplicating the genes for cell division.
d. Proteins that are to be secreted by the cell are generally synthesized by
membrane-bound ribosomes.
e. Active transport involves movement of molecules into a cell against their
APPENDIX A: PRESCRIBED LEARNING OUTCOMESThe Prescribed Learning Outcomes for Grade 12 are listed under each of the following organizers:
A: Cell Biology (Cell Structure) B: Cell Biology (Cell Compounds) C: Cell Biology (Biological Molecules) D: Cell Biology (DNA) E: Cell Processes (Protein Synthesis) F: Cell Processes (Cancer) G: Cell Processes and Applications (Transport Across Cell Membrane) H: Cell Processes and Applications (Enzymes) I: Human Biology (Digestive System) J: Human Biology (Circulatory System - Circulation and Blood) K: Human Biology (Circulatory System - Heart Structure and Function) L: Human Biology (Respiratory System) M: Human Biology (Nervous System - Neuron, Impulse Generation, and Reflex Arc) N: Human Biology (Nervous System - Divisions of the Nervous System and the Brain) O: Human Biology (Urinary System) P: Human Biology (Reproductive System)
The Prescribed Learning Outcomes for Biology 12 have been coded for ease of reference for those compiling provincial exams.
A1. describe the following cell structures and their functions:
cell membrane
mitochondria
smooth and rough endoplasmic reticulum
ribosomes
Golgi bodies
vesicles
vacuoles
lysosomes
nuclear envelope
nucleus
nucleolus
chromosomes
A2. identify the functional interrelationships of cell structures
A3. identify the cell structures in diagrams and electron micrographs
Cell Biology (Cell Compounds)
It is expected that students will:
B1. describe how the polarity of the water molecule results in hydrogen bonding
B2. describe the role of water as a solvent, temperature regulator, and lubricant
B3. distinguish among acids, bases, and buffers, and indicate the importance of pH to biological systems
Cell Biology (Biological Molecules)
It is expected that students will:
C1. demonstrate a knowledge of synthesis and hydrolysis as applied to organic polymers
C2. distinguish among carbohydrates, lipids, proteins, and nucleic acids with respect to chemical structure
C3. recognize the empirical formula of a carbohydrate
C4. differentiate among monosaccharides, disaccharides, and polysaccharides
C5. differentiate among starch, cellulose, and glycogen
C6. list the main functions of carbohydrates
C7. compare and contrast saturated and unsaturated fats in terms of molecular structure
C8. describe the location and explain the importance of the following in the human body: neutral fats, steroids, phospholipids
C9. draw a generalized amino acid and identify the amine, acid (carboxyl), and R-groups
C10. differentiate among the primary, secondary, tertiary, and quaternary structure of proteins
C11. list the major functions of proteins
C12. relate the general structure of the ATP molecule to its role as the "energy currency" of cells
Cell Biology (DNA)
It is expected that students will:
D1. name the four bases in DNA and describe the structure of DNA using the following terms:
nucleotide (sugar, phosphate, base)
complementary base pairing
double helix
hydrogen bonding
D2. describe DNA replication with reference to three basic steps:
"unzipping"
complementary base pairing
joining of adjacent nucleotides
D3. define recombinant DNA
D4. describe three uses for recombinant DNA
D5. compare and contrast the general structural composition of DNA and RNA
Cell Processes and Applications (Protein Synthesis)
It is expected that students will:
E1. demonstrate a knowledge of the basic steps of protein synthesis, identifying the roles of DNA, mRNA, tRNA, and ribosomes in the processes of transcription and translation
E2. determine the sequence of amino acids coded for by a specific DNA sequence, given a table of mRNA codons
E3. give examples of two environmental mutagens that can cause mutations in humans
E4. use examples to explain how mutations in DNA affect protein synthesis and may lead to genetic disorders
Cell Processes and Applications (Cancer)
It is expected that students will:
F1. describe cancer with respect to:
abnormal nuclei
disorganized and uncontrolled growth (anaplasia)
lack of contact inhibition
vascularization
metastasis
F2. list the seven danger signals that may indicate the presence of cancer
F3. differentiate between a proto-oncogene and an oncogene
F4. use examples to outline the roles of initiators and promoters in carcinogenesis
F5. demonstrate a knowledge of how a virus can bring about carcinogenesis
Cell Processes and Applications (Transport Across Cell Membrane)
It is expected that students will:
G1. apply knowledge of organic molecules to explain the structure and function of the fluid-mosaic membrane model
G2. explain why the cell membrane is described as "selectively permeable"
G3. compare and contrast the following: diffusion, facilitated transport, osmosis, active transport
G4. explain factors that affect the rate of diffusion across a cell membrane
G5. describe endocytosis, including phagocytosis and pinocytosis, and contrast it with exocytosis
G6. predict the effects of hypertonic, isotonic, and hypotonic environments on animal cells
G7. demonstrate an understanding of the relationship and significance of surface area to volume, with reference to cell size
Cell Processes and Applications (Enzymes)
It is expected that students will:
H1. demonstrate an understanding of the following terms: metabolism, enzyme, substrate, coenzyme, activation energy
H2. identify the source gland for thyroxin and relate the function of thyroxin to metabolism
H3. explain the "lock and key" model of enzymatic action
H4. identify the role of vitamins in biochemical reactions
H5. differentiate between the roles of enzymes and co-enzymes in biochemical reactions
H6. apply knowledge of proteins to explain the effects on enzyme activity of pH, temperature, substrate concentration, enzyme concentration, competitive inhibitors, and heavy metals
H7. devise an experiment using the scientific method
Human Biology (Digestive System)
It is expected that students will:
I1. identify and give a function for each of the following:
mouth
tongue
teeth
salivary glands
pharynx
epiglottis
esophagus
cardiac sphincter
stomach
pyloric sphincter
duodenum
liver
gall bladder
pancreas
small intestine
appendix
large intestine (colon)
rectum
anus
I2. relate the following digestive enzymes to their glandular sources and describe the digestive
reactions they promote:
salivary amylase
pancreatic amylase
proteases (pepsin, trypsin)
lipase
peptidase
maltase
nuclease
I3. describe swallowing and peristalsis
I4. identify the components and describe the digestive actions of gastric, pancreatic, and intestinal juices
I5. identify the source gland for and describe the function of insulin
I6. explain the role of bile in the emulsification of fats
I7. list six major functions of the liver
I8. demonstrate the correct use of the dissection microscope
I9. examine the small intestine and describe how it is specialized for digestion and absorption
I10. describe the functions of E. coli in the colon
Human Biology (Circulatory System--Circulation and Blood)
It is expected that students will:
J1. describe and differentiate among the five types of blood vessels
J2. identify and give functions for each of the following:
subclavian arteries and veins
jugular veins
carotid arteries
mesenteric arteries
anterior and posterior vena cava
pulmonary veins and arteries
hepatic vein
hepatic portal vein
renal arteries and veins
iliac arteries and veins
coronary arteries and veins
aorta
J3. demonstrate safe and correct dissection techniques
J4. distinguish between pulmonary and systemic circulation
J5. identify and describe differences in structure and circulation between fetal and adult systems
J6. demonstrate a knowledge of the path of a blood cell from the aorta through the body and back to the left ventricle
J7. list the major components of plasma
J8. identify and give functions of lymph capillaries, veins, and nodes
J9. describe the shape, function, and origin of red blood cells, white blood cells, and platelets
J10. demonstrate the correct use of the compound microscope
J11. explain the roles of antigens and antibodies
J12. describe capillary-tissue fluid exchange
Human Biology (Circulatory System--Heart Structure and Function)
It is expected that students will:
K1. identify and give functions for each of the following:
left and right atria
left and right ventricles
coronary arteries and veins
anterior and posterior vena cava
aorta
pulmonary arteries and veins
pulmonary trunk
atrioventricular valves
chordae tendineae
semi-lunar valves
septum
K2. describe the location and functions of the SA node, AV node, and Purkinje fibres
K3. describe the autonomic regulation of the heartbeat by the nervous system
K4. relate factors that affect and regulate blood pressure to hypertension and hypotension
K5. demonstrate the measurement of blood pressure
K6. distinguish between systolic and diastolic pressures
Human Biology (Respiratory System)
It is expected that students will:
L1. identify and give functions for each of the following:
larynx
trachea
bronchi
bronchioles
alveoli
diaphragm and ribs
pleural membranes
thoracic cavity
L2. explain the roles of cilia and mucus in the respiratory tract
L3. explain the relationship between the structure and function of alveoli
L4. compare and contrast the mechanics of the processes of inhalation and exhalation
L5. describe the interaction of the lungs, pleural membranes, ribs, and diaphragm in the breathing process
L6. explain the roles of carbon dioxide and hydrogen ions in stimulating the breathing centre in the medulla oblongata
L7. describe the exchange of carbon dioxide and oxygen during internal and external respiration
L8. distinguish between the transport of in the blood by explaining the roles of oxyhemoglobin, carbaminohemoglobin, reduced hemoglobin, and bicarbonate ions
Human Biology (Nervous System--Neuron, Impulse Generation, and Reflex Arc)
It is expected that students will:
M1. identify and give functions for each of the following: dendrite, cell body, axon
M2. distinguish among sensory, motor, and interneurons with respect to structure and function
M3. explain the transmission of a nerve impulse through a neuron, using the following terms:
resting and action potential
depolarization and repolarization
sodium and potassium gates
sodium-potassium pump
recovery period
threshold ("all-or-none response")
M4. relate the structure of a myelinated nerve fibre to the speed of impulse conduction
M5. identify the major components of a synapse
M6. explain the process by which impulses travel across a synapse
M7. demonstrate knowledge of how neurotransmitters are broken down in the synaptic cleft
M8. relate the structure of a reflex arc to how it functions
Human Biology (Nervous System--Divisions of the Nervous System and the Brain)
It is expected that students will:
N1. contrast the locations and functions of the central and peripheral nervous systems
N2. differentiate between the functions of the sympathetic and parasympathetic divisions of the autonomic nervous system
N3. identify the source gland for adrenalin and explain its role in the "fight or flight" response
N4. identify and give functions for each of the following:
medulla oblongata
cerebrum
thalamus
cerebellum
hypothalamus
corpus callosum
N5. explain how the hypothalamus and pituitary gland interact as the neuroendocrine control
centre
Human Biology (Urinary System)
It is expected that students will:
O1. identify and give functions for each of the following:
kidney
ureter
urethra
urinary bladder
renal cortex
renal medulla
renal pelvis
O2. identify and give functions for each of the following:
nephron
glomerulus
Bowman's capsule
afferent and efferent arterioles
peritubular capillary network
proximal and distal convoluted tubules
collecting duct
loop of Henle
O3. contrast the blood in the renal artery and the renal vein with respect to urea and glucose
content
O4. identify the source glands for ADH and aldosterone and explain how these hormones are regulated
O5. relate ADH, aldosterone, and the nephron to the regulation of water and sodium levels in the blood
Human Biology (Reproductive System)
It is expected that students will:
P1. identify and give functions for each of the following:
testes (seminiferous tubules and interstitial cells)
epididymis
ductus (vas) deferens
prostate gland
Cowper's glands
seminal vesicles
penis
urethra
P2. demonstrate a knowledge of the path of sperm from the seminiferous tubules to the urethral
opening
P3. list the functions of seminal fluid
P4. identify the tail, midpiece, head, and acrosome of a mature sperm and state their functions
P5. describe the functions of testosterone
P6. demonstrate a knowledge of the control of testosterone levels by the endocrine system
P7. identify and give a function for each of the following:
ovaries (follicles and corpus luteum)
oviducts (fallopian tubes)
uterus
cervix
vagina
clitoris
P8. describe the functions of estrogen
P9. describe the sequence of events in the ovarian and uterine cycles
P10. demonstrate knowledge of the control of the ovarian and uterine cycles by hormones
P11. demonstrate knowledge of a positive feedback mechanism involving oxytocin
P12. describe the hormonal changes that occur as a result of implantation
Table of Contents
Province of British ColumbiaMinistry of EducationCurriculum Branch ?1996 Copyright